Date of Graduation

Fall 2016

Degree

Master of Science in Materials Science

Department

Physics, Astronomy and Materials Science

Committee Chair

Robert A Mayanovic

Keywords

thin films, Raman, SEM, XPS, pulsed laser deposition

Subject Categories

Materials Science and Engineering

Abstract

Pulsed Laser Deposition (PLD) technique, with its vast tunability in terms of thin film fabrication has been the center of this study. By changing the temporal component of the laser source used for deposition into the femtosecond (fs) regime, interesting structural, morphological changes can be achieved which may prove to be beneficial for photocatalytic applications. In particular, molybdenum oxide thin films, which are the less well-studied and potentially newer candidates for photocatalysis applications have been chosen for investigation. Hence, a detailed characterization study of molybdenum oxide thin films synthesized using femtosecond-based (f-PLD) and nanosecond-based (n-PLD) techniques, was carried out in terms of their structural, morphological, surface chemical/ electronic states and vibrational properties using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. The f-PLD technique was found to produce more favorable molybdenum oxide thin films deposited on glass for surface-related applications, in terms of having a higher surface to volume ratio, than the n-PLD technique. A related simultaneous study of substrate-based effect on the thin films produced using n-PLD system, also revealed both variation among the morphological, structural, and electronic (in terms of Mo oxidation state) properties depending upon the nature of the substrate used to synthesize the molybdenum oxide thin films. Special cases of thin films on epitaxial substrates (Si, sapphire) have been characterized to determine the parameters necessary for fabricating highly-textured thin films with large surface-area to volume ratio, which is key to efficient photo-catalysts.

Copyright

© Krishna Harsha Puppala

Available for download on Saturday, December 15, 2018

Open Access

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